1. Field of The Invention
The present invention relates to a polyacetal resin composition and an insert molded article comprising the same. More particularly, the present invention is concerned with a polyacetal resin composition having high mechanical strength retentivity, which comprises a polyacetal resin having a specific, relatively low melting temperature, a specific bisamide in a specific amount and a specific monoamide in a specific amount, and is also concerned with an insert molded article comprising the same.
The polyacetal resin composition of the present invention has excellent weatherability, specifically resistance to cooling-heating cycles (hereinafter, frequently referred to simply as "cooling-heating cycle resistance"), i.e., mechanical strength retentivity during cooling-heating cycles. For example, in the polyacetal resin composition of the present invention, not only the occurrence of whitening, crazing or cracking but also the lowering in impact resistance can be suppressed even after the polyacetal resin composition experiences repeated cooling-heating cycles.
The polyacetal resin composition of the present invention exhibits excellent cooling-heating cycle resistance with respect to the mechanical strength and, therefore, can be advantageously used in various applications where repeated heating-cooling cycles are necessarily experienced and where, hence, use of conventional polyacetal resins has been restricted. Therefore, the polyacetal resin composition of the present invention can be advantageously used as material for parts in various industrial fields. Also, an insert molded article comprising the above-mentioned polyacetal resin composition and a shaped part unified with the resin composition by insert molding, exhibits excellent cooling-heating cycle resistance with respect to the mechanical strength, so that, even after the insert molded article experiences repeated cooling-heating cycles, it does not suffer either appearance deterioration, such as whitening due to fine crazing, or a lowering in impact resistance. Thus, the insert molded article of the present invention can be used for a prolonged period of time, without suffering crazing or cracking.